The invention relates to processes for selectively depositing materials on a substrate using a supercritical fluid, and more particularly to processes for depositing materials on a semiconductor substrate using a supercritical fluid.
As the demand for ever-smaller silicon devices continues, and as resolution continues below the sub-micron level, the need for uniform and precise processes for depositing conductive pathways and interconnects is increasing. It is also desirable for such processes to proceed rapidly. For example, it is frequently desired to form metal-containing materials in and on semiconductor substrates. The metal-containing materials can be incorporated into integrated circuit devices, and/or can be utilized for formation of conductive interconnects between integrated circuit devices.
Wai et al, U.S. Pat. No. 6,653,236, describe methods of forming metal containing films over surfaces of semiconductor substrates using a supercritical fluid that contains metal forming precursors dispersed therein. A supercritical fluid is a composition that exists in a quasi-liquid state above a defined critical pressure and a critical temperature for the composition. For example, carbon dioxide becomes a supercritical fluid at temperatures above 31° C. and pressures above 1073 psi (73 atmospheres). Typical working conditions for supercritical CO2 are in the range of from about 60-100° C. and 1500-4500 psi. The use of supercritical fluids permits much greater amounts of precursors and/or reactants to be dissolved or dispersed than prior CVD (chemical vapor deposition) processes.
Processes such as chemical vapor deposition and deposition in supercritical fluids result in the formation of conformal coatings. However, in most, if not all instances, excess deposited material must be removed by either physical or chemical planarization, or a combination of physical and chemical planarization, before further processing of the semiconductor structure can take place. This requirement adds additional steps to the fabrication process, especially where multiple deposits are made on the substrate during the semiconductor device fabrication process.
Accordingly, there remains a need in the art for processes that can provide conformal coatings and layers in a semiconductor fabrication process but which eliminate the need for chemical and/or physical planarization of the deposited material.